In 1987, in his capacity as PLO legal advisor, Law Professor Francis Boyle drafted its 1988 Declaration of Independence. He predicted it would be an "instantaneous success." De jure UN membership would be achieved.
Palestine then met basic requirements needed for statehood. They include:
A determinable (not necessarily fixed) territory. Its borders are negotiable. The new state is comprised of Gaza, the West Bank and East Jerusalem. Palestinians have lived there for millennia. They rightfully deserve universally recognized sovereignty.
They have a fixed population. They're a legitimate state with a functioning government. It's peace loving. It accepts UN Charter provisions and can administer them. It's willing to do so. In 1988, Arafat declared the PLO as Palestine's Provisional Government.
It has the capacity to enter into relations with other states. On December 15, 1988, The General Assembly recognized Palestine's legitimacy. It gave it observer status.
Then and now, Palestine satisfies essential criteria. All UN Charter states (including America and Israel) provisionally recognized Palestinians as independent in accordance with UN Charter article 80(1) and League Covenant article 22(4).
As the League of Nations' successor, the General Assembly has exclusive legal authority to designate the PLO as the Palestinian peoples' legitimate representative.
The Palestine National Council (PNC) is the PLO's legislative body. It's empowered to proclaim the existence of Palestine. According to the binding 1925 Palestine Citizenship Order in Council, Palestinians, their children and grandchildren automatically become citizens. So do diaspora Palestinians.